Even though it was disappointing compared to the original Dark Souls, I still have to say Dark Souls 2. So strong are those games, that a weaker version is still among the best games of the year.
Other notable contestants are TLoU Remastered (and this would easily win but I'm not sure I want to make it eligible), Divinity Original Sin (rising, but still not at the top) and.. Plants vs. Zombies: Garden Warfare (on PC, the PC port is actually excellent, go and buy it!).
Still more games I'd like to mention: The Banner Saga, Might&Magic X, Titanfall beta (hardly played the release version, I need to give it another try), Diablo 3: RoS, Wargame: Red Dragon, Tropico 5. And a dozen others.